Rosin size



Nov. l, 1938. A Q DRESHHELD m- AL 2,134,912

ROSIN SIZE Original Filed May 1l, 1935 n IW n PMM Nev. i, 193s BDBIN miArthur C.

Dreelleld. Kalamaaoo Henry A. Johnstone, Savannah,

alalgnmen by meane ,Niemand Getaldrnnn. te. to Hercules Powder company,Wilmington, Del.. a corporation of A Delaware application May 11 1935,Serial No.

Divided and thla application March 2.

1936, Serial No. 66,69 l

6 Claims. (Cl. 134-21) This invention relates to improvements in rosinance with our invention comprises a reactionproduct of abietic acid, orequivalently of rosin. and caustic alkali, the reagents being reacted inproportions such that the rosin size productis free or substantiallyfree of saponiiiable substance. i. e., more particularly, free orsubstantially'free oi' unsaponifled rosin and/or excess or unreactedcaustic alkali. The rosin size'product in accordance with our inventionis more specically characterized by the fact that it is in the form ofnon-tacky, discrete particles having a cellular structure rendering themporous, and a minimum moisture con- 25 tent. The rosin size product isessentially dry and at the same time, by virtue of its characteristieindicated and more particularly by virtue of the cellular structure ofthe discrete particles, is rapidly and completely soluble in cold water.

'Ihe rosin size in accordance with our invention is of substantialadvantage from the pracf tical standpoint inasmuch as it will notdeteriL orate in shipment or storage and can be packed in paper bags,and inasmuch as it may be dis- 35 solved in water rapidly and easily'without the necessity for heating, Imechanical agitation, or otheraidsheretofore found necessary in dissolving rosin sizes.

The process for producing the rosin size of our invention, generallyspeaking, involves the saponification of abietic acid or rosin withcaustic alkali and on completion of the saponication,

discharging the superheated reaction mass into an atmosphere maintainedat a relative humidity 45 below or about 78%, it having been found thata relative humidity of below or about '78% is critical for theproduction of a rosin size having the characteristic of substantialdryness or low moisture content possessed by the rosin size contemplatedby our invention. lIn other words, the rosin size in accordance with ourinvention can be produced where the reaction mass is discharged into anatmosphere having a. relative humidity below about '78%.` By relativehu- 55 midity we mean the weight of water vapor,

4volume of air, divided by the weight which would expressed as apercentage, contained in a given be contained in the same volume ofsaturated air r at the same temperature.

For preferred operatiomthe Vrelative humidity is maintained about orbelow '12% and this secures very satisfactoryresults. As the relativehumidity rises above this, less ldesirable results are secured and whenthe relative humidity exceeds '18% or 80%.' thedry matterdecreasesrapidly, and therefore, we recommend and in practice aim to maintain therelative humidity at about 72% or below. Superheat or superheating isusedhere as indicating a liquid heat above its boiling point withoutconverting it into vapor, as results in the method hereinafter de-ftailed. A

More particularly, the method in accordance with our invention comprisesdischarging the superheated saponified abietic acid or rosin undervpressure 4into an enclosed chamber, lthrough which air maintained at arelative humidity below or about 78%, which is critical, is circulated.

Various more specific details comprised in the process in accordancewith our inventiony will appear from the more detailed of hereinafter.

The apparatus employed in vproducing the size of our invention from thebroad standpoint comprises a combination of elements wherein thesaponication of abietic acid or rosin with caustic alkali is eiected forsuperheating it under pressure, for discharging the reaction mass, forreceiving the discharged size and for insuring the maintenance of therelative humidity of the atmosphere into which the reaction mass or sizeis discharged at or below about the critical relative humidity of 78%,

Further and more specific details of the apparatus will be made apparentfrom the detailed description of a preferred embodiment thereofhereinafter. y

Having thus indicated in afgeneral way4 the nature and .purpose ofthisginvention, we will proceed to a more detailed description thereofwith; reference to the accompanying drawing, wherein:

The signal figure is a fragmentary view in side elevation of anapparatus adapted for the carrying out of our process for the productionof the product. L

Referring to the drawing, l indicates an' autoclave provided with apressure gauge 2 and an agitator 3 driven as shown from a motor 24. Theautoclave is jacketed, the jacket being connected description there-Ainto it a discharge'nozzle I4.

or provided with steam coils .(not shown) whereby rosin supplied to thetank 8 may be `melted and maintained in a molten condition. The tank 8is connected to the autoclave' .by means of a valved conduit 9, by whichmolten'rosin in a predetermined batch or quantity may be run into theautoclave. Adjacent the autoclave is positioned a tank I0 adapted tocontain a supply of caustic soda solution. The tankID is connected `witha supply or source of air under pressure through a valved"conduit I Iand the tank ,isl also connected with the bottom of the autoclave by avalvedvconduit I2. It will be noted that caustic soda solution in tankI0 may be discharged into the autoclave by means of airpressure admittedto tank Illthrough conduit II. i

An enclosed blow chamber I3 has Yprojecting The nozzle is connectedthrough a valved conduit I5 with the bottom of the autoclave; .Thebottomof the chamber I'3 is preferably formed in a V shape and islprovided with a longitudinal opening at its low point through which theproduct rI6 collecting in the chamber falls upon a conveyor belt I'l bywhich the product is carried to a convenient place for packing orstorage.

The blow chamber I3 is provided with means for the admissionof air,such, for example, as louvers I8, adjacent which are positioned heatingvelements I9 adapted to be connected to a suitable source of heat,l asfor example, steam. Alterna-y tively, the heating elements may bereplaced by electrical heating elements or the like, by which thetemperature of the air entering the chamber I3 may be raised.

From the top of the chamber, a conduit 20 leads to the suction side of asuitably driven exhaust blower., .2I by-which air is drawn through thechamber. The discharge from the blower 2| is connected to a' conduit 22leading to a separator 23. In the conduit 20, through which, as has beenindicated, air is drawn from the chamber by the blower 2|, andpreferably adjacent the point of connection of the conduit 20 with thechamber, is placed a humidostat 25, adapted to respond to the relativehumidity of the air leaving the chamber I3. By any suitable arrangement,electrical or otherwise, the humidostat 25 is arranged to control thetemperature of the air entering the chamber through the louvers I8 bycontrol of the heating elements I9. drating means might be employed, butthe apparatus as illustrated is highly practical.

The heating ofthe incoming air into the blowl chamber is not for ythepurpose of heating the air, but merely for the purpose of maintaining '8is run into the autoclave I. yto a temperature of about 275 F. beforeits in- An air dehyof air drawn through the blow chamber should at leastbe 1200 cubic feet per minute.

With respect to the apparatus above described it will be appreciatedthat the apparatus may comprise-a single autoclavevand means ofdischarge, in which case the chamber I3 will be i of suitable sizerelative to the capacity of the autoclave, or a plurality of autoclavesand means ofdischarge may be associated with a single chamber ofa sizerelative to the combined capacity of the autoclaves, or the severalreaction means may be manipulated to effect a continuous, discharge tothe chamber.

A typical installation, for example, may comprise a series of veautoclaves arranged in line adjacent one end of a drying chamber, eachautoyclave being provided with a. discharge nozzle within the chamber.In such an installation, assuming that the combined capacity of theautoclaves is ve tons of finished product per charge, the chamber I3should be about fty feet long, thirty feet wide and forty feet high, anddesirably the Walls of the chamber are insulated in order to avoid lossof heat therethrough.

In the operation of the apparatus in accordance with our invention, asdetailed above, for the carrying out of the method in accordance withour invention, molten rosin from the tank The rosin is heated troductioninto the autoclaver and the autoclave, through the introduction ofheating medium through conduit II into its jacket, is brought to asimilar temperature. The tank ID contains an aqueous solution of causticsoda of a concentration within about the range of 25% to about 50%(preferably 40%) caustic soda, by weight, and the solution in tank I0 isbrought to a temperature of about 220 F. to 275 F. by any suitablemeans, such as a steam coil (not shown) within the tank.

Molten rosin in a desired quantity having been introduced into theautoclave, an amount oi' caustic soda solution containing an amount ofcaustic suicient to saponify the amount of rosin previously introducedinto the autoclave is then blown into the bottom of the autoclavethrough conduit I2, by the introduction of air under pressure into thetank I0, through conduit II. The amount of caustic soda is such that oncompletion of saponiiication the product does not contain in excess ofabout. 2.5% free rosin or 0.5% free caustic soda. We find that 12.1% ofdry alkali based on dry rosin is preferable for gum rosin and 11.7% forwood rosin, depending upon their saponication number.

'The caustic soda solution is blown upwardly through the molten rosin inthe autoclave and the agitator 3 in the autoclave is operated tointermingle the rosin and the solution while, at the same time, thetemperature within the autoclave is maintained within the range of 275F. to 375F. until saponication is completed. During the reaction in theautoclave, a pressure which is due largely to the evolution of steamfrom the water of the caustic solution at the temperature used ismaintained. This pressure is preferably held between pounds vand 125pounds gauge for the temperature stated.

It will be noted that the reaction is carried out in the autoclave underpressure and in the absence of air, i. e., in the presence of the steamand vapor evolved from the reaction mass. When,

the reaction is complete, the reaction mass or saponied rosin Within theautoclave contains v about 15% to '20% moisture, n; being-noted ,that

loss of -any substantial amount of moisture is avoided. Hence, hardeningand stiiening of the reaction. mass is avoided and the latter is in amobile state due to its moisture content.

On completion of the reaction, the reaction quently the air and then themass is discharged into the chamber I3 through the nozzle I4, ailattened pipe having been found to be very satisfactory, the dischargebeing effected under constant pressure through conduit I5 by theintroduction of air under pressure at the top of the autoclave throughthe conduit 6. The discharge pressure is preferably held between 100Apounds and 125 pounds gauge.

, Prior to the discharge of the saponied rosin into the chamber I3, theblower 2| is started and a circulation of air through the chamber is setup. It will be noted. that air enters the chamber throughthe louvers I8and is-withdrawny therefroml through conduit 20. As the circula- (7vtion of air starts, the humidostat 25 responds to the relative humidityof the air. The humidostat, being arranged to control temperature of theair entering the chamber through the louvers I8 through control of theheating elements I9, is adjusted to maintain the relative humidity ofthe air passing out of the chamber and consewithin the chamber at orbelow 78%.

The-saponied rosin is 'discharged into the chamber I3 in a iinelysubdivided state. The finely subdivided particles are of a substantiallyuniform size, and since the interior of the chamfber is underatmospheric pressure, there is a sudden reduction in pressure on, andthe simultaneous ne subdivision of, the superheated deleterious actionwhich might result from pro` longed exposure to heat.

As the saponied rosin is discharged into the chamber and the yfinelysubdivided particles thereof are relieved of moisture and gases andvapors, the moisture and gases or vapors are carried out of the chamberunder the iniluence of the blower' 2I through the conduit 20 and the dryi'lnely divided particles of saponiiled rosin having a .cellularstructure fall to the bottom of the chamber and pass to the conveyorbelt I'I.

The moisture removed from the nely subdivided particles of saponiedrosin, which is picked up and carried from the chamber lI 3 by the aircirculating therethrough, tends to increase the relative humidity of theair in the chamber. Increasing the relative humidity of the air in thechamber to a point above about 78% relative humidityI causes thehumidostat in conduit 20 to exert a control upon the heatingelements I9,such that the temperature of the air in the chamber is increased andconsequently also the relative humidity of the air in the chambermaintained at or below about 78%.

It fwill be noted that in practical operation the relative humidity ofthe air in the chamber Il is fixed well below the 78% before dischargeof saponifled rosin thereinto and that the heating elements I9controlled by the humidostat are arranged so that the relative humidityin the chamber is not .at any time permitted to exceed about '18%relative humidity during the discharg of saponified rosin into thechamber.

The air leaving the chamber I3 through the conduit carries some iineparticles of the dried rosin size, such particles, however, beingrecovered in the separator 23 through which the l air is discharged.

It will be appreciated that various modiiications may be made in theapparatus as detailed l above and in the carrying out of the process asdetailed above without departure from' the scope of our invention;

The procedure in accordancel with our invention is of especial advantagein enabling the production of a highgrade size with wood rosin; as forexample-FUE'` rosin or even low grade B wood rosin, since the greenishcoloring matter oi` the wood rosin, heretofore carried into the size andpaper treated therewith, is violatilized, destroyed, or removed from thesize under the conditions of production in accordance with, ourinvention;`

It will be appreciated that from the process standpoint our inventioncomprises. essentially discharging and drying superheated saponiedabietic acid or rosin in an atmosphere having a relative humidity not inexcess of 78%, and that from the apparatus standpoint our inventioncomprises essentially a .combination of elements for the saponiflcationand discharge of abietic acid or rosin and for controlling' the relativehumidity of the atmosphere in which the saponified abietic acid or rosinis discharged within the limit contemplated by the process.

'I'he rosin size made in accordance with our invention comprises, as hasbeen indicated, discrete particles having a cellular structure renderingthem porous. 'I'he particles are charac` terized by the fact that theyare non-tacky, by the fact that they are substantially dry or have amoisture content not in excess of about'8%, by

their substantial freedom from saponiflable sub-` stances-moreparticularly, no more than 2.5% of unsaponied rosin or 0.5% o-f causticalkaliand by their rapid solubility in cold water, andV 'theirsubstantial freedom from volatile organic characterized by being free orsubstantially free of saponiflable substances, is in the form ofnontacky discrete particles having a cellular structure rendering themporous and having a minimum moisture content, the size being in eilectessentially dry, and is rapidly and completely soluble in cold water.Owing to the iluily character of the product, it is sometimes compressedin packing for shipment or storage, and while this somewhat modiiies itsfluffy character, it does 'not destroy its non-tacky characteristics andits complete solubility, the compressing being merely for the purpose ofreducing the volume, as stated.

Having thus vdescribed our invention, what we claim as new and desire tosecure by Letters uct of rosin and caustic alkali in the form ofnon-caking, non-tacky discrete, cellular particles, containing not over0.5% free alkali and essentially no unsaponied rosin and characterizedby porosity, by a moisture content of not in excess of about 8%, byfreedom from volatile products and by rapid and substantially completesolubility in cold water.

3. A dry rosin size comprising a reaction product of rosin and causticvalkali in the form of non-caking, non-tacky, discrete, cellularparticles, containing not over aboutV 2.5% of unsaponied rosin andessentially no free or unreacted caustic soda, characterized byporosity, by a moisture content of not in excess of about 8%, by freedomfrom volatile products, and by rapid and substantially completesolubility in cold water.

4. A dry rosin size comprising a .reaction'product of abietic acid andcaustic alkali in the form ,lof non-tacky, discrete particles,characterized 4by a moisture content not in excess of about 8%,.

by freedom from volatile products, by a cellular` structure, by rapidand substantially complete solubility in cold water, by containing notover about 2.5% of unsaponied abietic acid and not l over about 0.5% offree or unreacted caustic soda..

5. A dry rosin size comprising a reaction product of abietic acid vandcaustic alkali in the form y of non-caking',l non-tacky, discrete,cellular par- A' ticles, containing notover 0.5% free alkali andessentially no unsaponifled abietic acid and characterized by porosity,by a, moisture content of not in excess of about 8%, by freedom fromvolatile products and by rapid and substantially complete solubility incold water.

6. A dry rosin size comprising a reaction product of abietic acid andcaustic alkali in the form of non-caking, non-tacky, discrete,cellularparticles, containing not over about 2.5% of unsaponied abieticacid and essentially no free or unreacted caustic soda, characterized byporosity, by a moisture content of not in excess of about 8%, by freedomfrom volatile products, and by rapid and substantially completesolubility in cold water.

ARTHUR C. DRESI-IF'IELD. HENRY A. JOHNSTONE.

